Bug 591167: border trenches should be triggered even if the edge only overlaps, but is not contained by the active range of the trench [r+a=dietrich]

browser/base/content/tabview/modules/utils.jsm

@@ -322,6 +322,20 @@ Range.prototype = {
     return false;
   },
 
+  // ----------
+  // Function: overlaps
+  // Whether the <Range> overlaps with the given <Range> or value or not.
+  //
+  // Paramaters
+  //  - a number or <Range>
+  overlaps: function Rect_overlaps(value) {
+    if (Utils.isNumber(value))
+      return this.contains(value);
+    if (Utils.isRange(value))
+      return !(value.max < this.min || this.max < value.min);
+    return false;
+  },
+
   // ----------
   // Function: proportion
   // Maps the given value to the range [0,1], so that it returns 0 if the value is <= the min,

browser/base/content/tabview/trench.js

@@ -382,7 +382,7 @@ Trench.prototype = {
   ruleOverlaps: function Trench_ruleOverlaps(position, range) {
     return (this.position - this.radius < position &&
            position < this.position + this.radius &&
-           this.activeRange.contains(range));
+           this.activeRange.overlaps(range));
   },
 
   //----------